Presently, the Office of Vehicle Safety Standards is considering new regulations relating to emergency door exits for school buses. Generally, these regulations will require school buses to have emergency doors which, when opened, automatically lock in an open position regardless of the orientation of the bus. These regulations will help ensure that children can easily exit from school buses in the event of an emergency.
Specifically, these regulations will require that school bus emergency doors be equipped with a device that (1) locks the doors in an open position past the point at which the door is perpendicular to the bus body, regardless of the bus orientation; (2) bears the weight of the door; and (3) provides a mechanism for releasing the door from its locked position and thus, allows the door to close. Accordingly, there is obviously a need for a locking device that meets these standards.
Furthermore, in emergency situations, children may not be able to push a heavy emergency bus door over 90.degree. at one time, especially if the bus is laying on its side, an obstruction prevents the door from opening that widely, or the bus is in water. Therefore, preferably, the locking device should lock the door open in several positions before locking the door in a final open position over 90.degree. from the closed position. Therefore, there is a need for a closure locking device which will lock a closure in various open positions.
Examples of locking hinges which lock a door in an open position and prevent it form closing until being released are disclosed in U.S. Pat. Nos. 294,746 issued on Mar, 4, 1884 to Straup et al; 917,768 issued on Apr. 13, 1909 to Jordan; 1,060,641 issued on May 6, 1913 to Sladden; 1,183,596 issued on May 16, 1916 to Sachse; 1,489,679 issued on Apr. 8, 1924 to Thornton; 2,966,697 issued on May 16, 1958 to Mintz; 2,146,460 issued on Feb. 7, 1939 to Beeler; 3,559,232 issued on Mar. 21, 1969 to Crane; and 3,629,900 issued on Dec. 28, 1971 to Beerli, Jr.
However, these prior locking hinges have several disadvantages. Many of these locking hinges do not automatically lock the door in an open position. Furthermore, with respect to the application of these devices to school buses, each manufacturer of school buses, i.e., Blue Bird, Am Tran, Carpenter and Thomas, currently uses different hinges on the emergency doors. These hinges do not lock the door in an open position, and replacing these current hinges with the prior locking hinges is inefficient and expensive. Additionally, many of these hinges can only be used in connection with certain types of doors. Furthermore, these hinges do not always provide the support and strength needed in emergency situations in applications such as school buses. Finally, many of the prior locking hinges have complicated release mechanisms which have many parts and are hard to manufacture.
Examples of hinges which hold a door in an open position, but do not lock it in an open position are disclosed in U.S. Pat. Nos. 769,035 issued on Aug. 30, 1904 to Walter; 975,097 issued on Nov. 8, 1910 to Wright; 1,125,265 issued on Jan. 19, 1915 to Carter; 1,429,416 issued on Sep. 19, 1922 to Fade; 1,440,713 issued on Jan. 2, 1923 to Ausbourne; 1,465,912 issued on Aug. 21, 1923 to Jensen; 1,946,837 issued on Feb. 13, 1934 to Clayton; 2,097,651 issued on Nov. 2, 1927 to Stangeland; and 2,427,384 issued on Sep. 16, 1947 to Bushko.
In view of the above, it is apparent that a need exists for a locking device that automatically locks a door in several open positions, can be easily released from any of the locked open positions, can be retrofitted to current hinges and can be used in connection with any type of hinge and closure. This invention addresses these needs in the art, along with other needs which will become apparent to those skilled in the art once given this disclosure.